Difficulty: Medium
Correct Answer: 64
Explanation:
Introduction / Context:The equation mixes logarithms with bases 8, 4, and 2 applied to the same x. Converting all to base 2 simplifies the problem to a single-variable linear equation.
Given Data / Assumptions:
Concept / Approach:Let y = log₂ x, so x = 2^y. Then log₄ x = y/2 (since 4 = 2^2) and log₈ x = y/3 (since 8 = 2^3). Substitute and solve for y, then recover x = 2^y.
Step-by-Step Solution:
Let y = log₂ xThen log₄ x = y/2 and log₈ x = y/3Sum: y/3 + y/2 + y = 11 ⇒ (2y + 3y + 6y)/6 = 11 ⇒ 11y/6 = 11 ⇒ y = 6Therefore x = 2^6 = 64Verification / Alternative check:Compute each term: log₂ 64 = 6, log₄ 64 = 3, log₈ 64 = 2; sum 6 + 3 + 2 = 11, confirming the solution.
Why Other Options Are Wrong:2, 4, and 8 yield sums far smaller than 11; only 64 produces the required sum.
Common Pitfalls:Forgetting the base-change scaling (dividing by 2 or 3) or mis-adding fractions can produce a wrong y value. Carefully use common denominators.
Final Answer:64
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